Circuit breaker



Dec. 10, 1968 aCDONALD ET AL 3,416,113

CIRCUIT BREAKER army/14w Filed May 4, 1967 United States Patent 3,416,113 CIRCUIT BREAKER John MacDonald, Edward J. Eden, and Franklin D.

Myers, Jackson, Mich., assignors to Mechanical Products, Inc., Jackson, Mich., a corporation of Delaware Filed May 4, 1967, Ser. No. 636,163 2 Claims. (Cl. 337-74) ABSTRACT OF THE DISCLOSURE A push-pull type aircraft circuit breaker in which a push-pull manual operator supports a slidable contact carrier. The contact carrier is positioned relative to a fixed contact by a laterally extending cross slide which is engaged with a current responsive bimetal and a latch element. The bimetal and latch extend generally parallel to the manual operator.

This application relates generally to circuit breakers and more particularly to an improved aircraft circuit breaker.

Background of the invention The instant invention is an improvement on the invention disclosed in Patent No. 3,287,523 which is assigned to the assignee of the instant invention.

Summary of the invention The invention lies in the provision of a novel bimetal that extends parallel to the manual operator slide and which floats laterally to precluding binding due to fiexure upon overload or due to manual operation. Further, the cross slide of the circuit breaker is provided with a roller latch that minimizes friction upon manual operation. Also, an improved latch facilitates calibration and maximizes manufacturing economy.

In the drawings FIGURE 1 is a side elevational view, partially in section, of an improved circuit breaker in accordance with the instant invention with the cover removed therefrom;

FIG. 2 is a cross sectional view taken substantally along the line 2-2 of FIGURE 1; 6

FIG. 3 is a cross sectional view taken substantially along the line 3-3 of FIGURE 1;

FIG. 4 is a view similar to FIGURE 3 showing the circuit breaker in the open and trip-free condition" due to flexure'of the current responsive bimetal or magnetic opening thereof; and

FIGQS, is a view similar to FIGURE 4 showing the circuit breaker in the open condition due to manual operation.

As best seen in FIGURE 1, a circuit breaker 10, in accordance with an exemplary constructed embodiment of the instant invention, comprises an enclosure 12 having a pair of exteriorly extending terminals 14 and 16 thereon. A threaded ferrule 18 extends exteriorly of the enclosure 12 for the guidance of a manual operator 20. The ferrule 18, in conjunction with a nut 22, provides a mounting means for the circuit breaker on a panelboard (not shown).

The manual operator 20 has an elongated stem portion 30 secured thereto as by an integral rivet 32. The stem 30 extends centrally of the circuit breaker 10, an upper end portion 34 thereof extending into a complementary slot 36 in the housing 12. A spring 40 normally biases the manual operator 20 downwardly as seen in FIGURE 1 of the drawings.

A movable contact carrier 50 has a central slot 52 therein for the slidable acceptance of the stem portion 30 of the manual operator 20. As seen in FIGURE 2, the contact carrier 50 has a resilient contact support arm 54 secured thereto for the support of a movable contact 56. The movable contact 56 is engageable with a fixed contact 58 to complete a circuit through the circuit breaker 10 as will be described.

A helical coil spring 60 is secured to an end portion 62 of contact support arm 54 and to a bracket 68 on the housing 12 so as to normally bias the contact carrier 50 downwardly relative to the housing 12 as seen in FIG- URE 2.

The contact carrier 50 has a laterally extending slot 70 therein for the acceptance of a slide 72. The slide 72 is movable internally of the contact carrier 50 under the infiuence of a current responsive bimetal 74. As best seen in FIGURE 3 of the drawings the current responsive bimetal 74 is interlocked with an end portion 76 of the slide 72 to control lateral movement thereof. The opposite end portion 78 of the slide 72 is normally seated on a latch 80 which in turn is secured to an ambient temperature compensating bimetal 82 so as to be controlled thereby.

It is to be noted that the current responsive bimetal 74 has one end portion 84 seated in a complementary seat 86 in the housing 12 and, in accordance with one feature of the instant invention, an opposite end portion 88 that is positioned by a helical compression spring 90 against a stop 92.

Similarly, one end portion 94 of the ambient compensating bimetal 82 is seated in a complementary seat 96 of the housing 12 and an opposite end portion 98 is controlled by a calibration screw 100.

The stem portion 30 of the manual operator 20 is provided with a notch 102 having an angular cam portion 104, in accordance with another feature of the instant invention, that is engageable with a slide roller 106. The .roller 106 is retained in a complementary slot 108 (FIG- URE 3) in the slide 72, as by staking. The roller 106 mimimizes friction between the stem 30 of the manual operator 20 and the slide 72.

The stem portion 30 of the manual operator 20 is interlocked with the contact carrier 50 by a pin 110 that is carried by the contact carrier 50 and is received in a complementary slot 112 in the stem 30.

As best seen in FIGURES 1, 4 and 5, the circuit breaker 10 may be provided with a magnetic trip device 118 compressing a core 120 having a coil 122 thereon. The core 120 is supported by the housing 12. The poles of the core 120 are disposed in closely spaced magnetic flux transfer relationship with the current responsive bimetal 74 to speed up the response of the circuit breaker 10 to a fault condition. The coil 122 is connected in series or parallel relationship with the bimetal 74 or eliminated as required. Similarly, the coil 122 can function as a heater,if desired, to speed up thermal response of the bimetal 74.

Closure of the circuit breaker from the condition shown in FIGURE 5 of the drawings to the condition shown in FIGURES 1 and 2 of the drawings is effected by upward pressure on the manual operator 20 until the slide roller 106 moves into the notch 102 in the stem 30 permitting the end 78 of the slide 72 to snap over the latch 80.

Upon the occurrence of an overload condition the center of the current responsive bimetal 74 flexes to the left, as seen in FIGURE 1 of the drawings, to draw the slide 72 to the left disengaging the end portion 78 thereof from the latch 80. When the slide 72 is disengaged from the latch 80 the plunger 50 is free to move downwardly relative to the housing 12 and stem 30 of the manual operator 20 under the bias of the spring 60. It is to be noted that, as seen in FIGURE 4, the spring 90 permits 3 the lower end 88 of the bimetal 74 to move to the left minimizing interference between the slide 72 and either the bimetal 74 or the stem 30.

As seen in FIGURE 5, manual opening of the circuit breaker 10 is effected by pulling downwardly on the manual operator 20 thereby biasing the cam surface 104 downwardly and moving the roller 106 and slide 72 to the left.

It is to be understood that the specific construction of the improved circuit breaker herein disclosed and described is presented for the purpose of explanation and illustration and is not intended to indicate limits of the invention the scope of which is defined by the following claims.

What is claimed is:

1. An electrical circuit breaker comprising,

an insulating housing,

a pair of terminals extending exteriorly of said housing,

a fixed contact connected to one of said terminals,

an elongated current responsive bimetallic element in said housing having one end supported thereby and a movable end,

stop means,

resilient means normally biasing the movable end of said bimetallic element against said stop means,

a latch supported by said housing,

a contact carrier having a movable electrical contact thereon engageable with said fixed contact,

a slide carried by said contact carrier and extending transversely to said current responsive element, said slide being controlled by an intermediate portion of said current responsive bimetal for movement relative to said contact carrier, the other end of said slide being engageable with said latch, deflection of said current responsive bimetal effecting disengagement of said slide from said latch permitting said contact carrier to move to the contacts open condition, the movable end of said bimetallic element being movable against the bias of said resilient means to facilitate opening movement of said contact carrier, and a manual operator operable to move said contact carrier to the contacts closed condition, said manual operator having means engageable with said slide to effect movement thereof relative to said latch to effect manual opening of said contacts. 2. A circuit breaker in accordance with claim 1 including a roller on said slide engageable with said manual 20 operator to minimize friction therewith.

References Cited UNITED STATES PATENTS 3,287,523 11/1966 MacDonald et al.

l/l968 Clarke 200-1l6 

